This invention relates to miticidal mixtures and method. More particularly, it relates to synergistic miticidal mixtures and method for preventing the destructive effects of pests such as mites in which a macrotetrolide compound represented by the formula ##STR2## wherein R.sub.1, R.sub.2, R.sub.3 and R.sub.4 are each selected from the group consisting of methyl and ethyl and known generically as polynactin is admixed with methyl N',N'-dimethyl-N-[(methyl-carbamoyl)-oxy]-1-thiooxamimidate (III) to achieve improved miticidal properties when applied to plants in significantly smaller amounts than would be required if each of the compounds were applied individually.
The prior art recognizes that certain macrotetrolide compounds may exhibit pesticidal properties individually or when combined with other compounds. U.S. Pat. No. 3,777,023 to Sagawa et al., for example, teaches that miticidal compositions of macrotetrolide antibiotics, such as polynactin, with organochloric, carbamate and organophosphorus pesticides demonstrate increased miticidal activity than the macrotetrolides individually.
U.S. Pat. Nos. 3,530,220 and 3,658,870 to Buchanan disclose that mixtures of certain chemical compounds of the class alkyl 1-carbamoyl-N-(substituted carbamoyl)thioformimidates such as oxamyl with other acaricides can be useful in preventing plant destruction from insects and mites.
While the above disclosures and others identify effective mite control agents, there is an everpresent need for developing improved miticides and mite ovicides capable of achieving desirable levels of pest control at low cost and high safety margins for the host plant.